ABIM - Large Vessel Vasculitis

Here are key facts for ABIM from the Large Vessel Vasculitis tutorial, as well as points of interest at the end of this document that are not directly addressed in this tutorial but should help you prepare for the boards. See the tutorial notes for further details and relevant links.

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1. GCA affects large vessels, particularly the branches of the external carotid artery, such as the temporal artery. 2. Typical demographic: women over 50 years old, especially of Northern European descent. 3. Clinical presentation:

• New-onset temporal headache
• Jaw claudication (pain when chewing)
• Scalp tenderness
• Visual symptoms (amaurosis fugax, blurred vision, possible permanent blindness)
• Polymyalgia rheumatica association (proximal muscle pain and stiffness)

4. Management principle: Start high-dose corticosteroids (e.g., prednisone 40–60 mg/day) immediately based on clinical suspicion — do not delay for biopsy. 5. Diagnosis confirmed with temporal artery biopsy (granulomatous inflammation, multinucleated giant cells). 6. Supporting labs: markedly elevated ESR and CRP. 7. Untreated GCA can cause permanent vision loss, stroke, and thoracic aortic aneurysm. 8. Takayasu arteritis involves granulomatous inflammation of the aorta and its major branches. 9. Typical demographic: young women (<40 years), especially of Asian descent. 10. Clinical presentation:

• Decreased or absent pulses (e.g., brachial, radial)
• Blood pressure difference between arms (>10 mmHg)
• Arm or leg claudication
• Bruits over subclavian or carotid arteries
• Hypertension (due to renal artery involvement)

11. Diagnosis is made via CT angiography or MR angiography showing stenosis or wall thickening. 12. First-line treatment is high-dose corticosteroids.

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1. Both GCA and Takayasu are granulomatous vasculitides targeting large vessels. 2. Histologic findings include:

• Granulomatous inflammation
• Multinucleated giant cells
• Destruction of the internal elastic lamina
• Intimal hyperplasia leading to luminal narrowing

3. In GCA, branches of the external carotid artery are primarily involved; in Takayasu, involvement focuses on the aortic arch and branches. 4. Temporal artery biopsy is gold standard for GCA but may have patchy involvement (false negatives possible). 5. Elevated ESR (>50 mm/hr) and CRP are nonspecific but strongly supportive. 6. Anemia of chronic disease may be present in both conditions. 7. Imaging for Takayasu should evaluate the full aorta and major branches (CT/MRI). 8. In GCA:

• Start corticosteroids immediately.
• If visual symptoms occur, hospitalize for IV methylprednisolone.

9. In Takayasu:

• Use systemic corticosteroids initially.
• Methotrexate or azathioprine may be used as steroid-sparing agents.

10. Monitor response with serial ESR and CRP.

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1. For GCA:

• Steroid taper guided by symptoms and inflammatory markers.
• Low-dose aspirin is often recommended to reduce stroke risk.
• Monitor for aortic aneurysm development (especially thoracic).

2. For Takayasu:

• Monitor for development of aortic aneurysms, renal artery stenosis, and aortic regurgitation.
• Annual imaging may be needed to detect progression.
• Antihypertensive therapy is often required if renal arteries are involved.

3. Chronic steroid use requires:

• Bone protection (calcium, vitamin D, bisphosphonates)
• Monitoring for hyperglycemia, infections, and myopathy

4. Tocilizumab (IL-6 receptor antagonist) is FDA-approved for relapsing GCA and can reduce steroid exposure. 5. In Takayasu, relapses are common; long-term immunosuppressive therapy may be necessary.